Pregnancy losses negatively affect the cattle industry, impacting economic indices and consequently the entire production chain. Early embryonic failure has been an important challenge in the embryo industry because proper identification of embryo death at the beginning of gestation is difficult. This review aimed to provide a better understanding on reproductive failure and the relationship between early embryonic loss and different reproductive biotechniques. This review also considers insights and possible strategies for reducing early embryonic loss. The strategies addressed are as follows: i) great impact of rigorous embryo evaluation on reducing embryo losses; ii) selection of recipients at the time of transfer, taking into account health and nutritional status, and classification of the corpus luteum using ultrasound, either in area or vascularization; and iii) paternal effect as one of the factors that contribute to pregnancy losses, with a focus on embryo transfer.

Oxidative stress (OS) induced by an imbalance in reactive oxygen species (ROS) levels in vitro impairs embryonic development. Here, we assessed the effects of alpha-lipoic acid (ALA) in in vitro production media on OS reduction, embryonic development, and cryotolerance of bovine embryos. We evaluated the effects of adding different concentrations of ALA (2.5, 5, 10, and 25 μM) to in vitro maturation (IVM) or in vitro culture (IVC) medium on embryonic development. We also determined the effects of adding ALA (25 μM) to the IVM and IVC medium in the same routine on the development and quality of embryos, ROS levels, and cryotolerance. Embryos were produced in vitro using conventional protocols for each treatment. The inclusion of ALA in the IVM and IVC media did not affect the development or quality of embryos; however, it reduced ROS levels in grade II embryos and increased hatching after 12 h on day 7 in grade I embryos and on day 8 in grade II embryos after warming. These findings prompt questions regarding the potential of ALA in improving embryo metabolism, considering the initial embryo recovery in the first few hours of embryo warming.

Productive performance and carcass characteristics of feedlot lambs fed corn grain silage rehydrated

Resumo Avaliou-se o flushing alimentar sobre a eficiência reprodutiva em 60 ovelhas Santa Inês, distribuídas em três grupos: (1) sem suplementação, (2) 0,50% e (3) 1,00% de suplementação do peso corporal. O suplemento continha milho, farelo de soja, aveia, calcário, fosfato bicálcico, mistura mineral, ureia e levedura, administrado três semanas antes e durante o acasalamento, que perdurou por 46 dias. Peso, condição corporal e ganho de peso foram medidos no início e no fim do período de alimentação. A produção de leite, o peso dos borregos e as medições biométricas foram registados até o desmame. A suplementação não afetou significativamente o peso das ovelhas, os índices de condição corporal ou produção de leite. As percentagens de nascimentos gemelares foram de 19%, 52,9% e 44,4% (P=0,08), respectivamente, para o grupo sem suplementação e para os grupos que receberam suplementos (0,50% e 1,00%). Durante a análise, constatou-se que o peso do cordeiro e as medidas biométricas não foram significativamente afetados pelo tratamento materno ou pelo sexo do cordeiro. Os borregos nascidos de partos simples eram mais pesados que os de partos gemelares (p<0,05), mas os pesos combinados dos gêmeos ao desmame eram mais elevados. As ovelhas com gêmeos tenderam (p<0,09) a ser mais eficientes do que aquelas com partos simples, desmamando 41 kg de cordeiros por 100 kg de peso corporal, em comparação com 36 kg nas ovelhas com nascimento único. Concluiu-se que o flushing não afetou o peso da ovelha nem a produção de leite, mas aumentou a taxa de nascimentos de gêmeos, melhorando a eficiência reprodutiva.

The study evaluated dietary flushing on reproductive efficiency in 60 Santa Ines ewes, divided into three groups: (1) no supplementation, (2) 0.50% and (3) 1.00% supplementation of body weight. The supplement contained corn, soybean meal, oats, lime, bicalcium phosphate, mineral mixture, urea and yeast, administered three weeks before and during mating, which lasted for 46 days. Weight, body condition and weight gain were measured at the beginning and end of the feeding period. Milk production, lamb weight and biometric measurements were recorded until weaning. Supplementation did not significantly affect the ewes' weight, body condition indices or milk production. The percentages of twin births were: 19%, 52.9% and 44.4% (P=0.08), respectively for the ewes in the control group and for those that received supplements (0.50% and 1.00%). Lamb weight and biometric measurements were not significantly affected by maternal treatment or the sex of the lamb. Lambs born from single births were heavier than those from twin births (P<0.05), but the combined weights of twins at weaning were higher. Ewes with twins tended (P<0.09) to be more efficient than those with single birth lambs, weaning 41 kg of lambs per 100 kg of ewe weight, compared to 36 kg for single birth ewes. Flushing did not affect ewe weight or milk production, but it did increase the rate of twin births, improving reproductive efficiency.